This invention relates to transmissions for vehicles with a drive engine and especially to such transmissions having multiple-step gear changes.
Such transmissions are useful in automatic transmission applications in which shifting times are determined and shifting procedures are initiated by an electronic control system taking particular parameters into account. Another area of application is in so-called semiautomatic transmissions having manual gear selection but providing automatic clutch actuation and a subsequent automatic additional shifting routine.
A multiple-step transmission with an additional highest-speed step is disclosed in European Patent No. 0,173,117 B1. In that case, during a shifting procedure, i.e., upon disengagement of the old gear and prior to engagement of the new gear, that additional highest-speed step, gear is connected through a single clutch to transfer a driving force to the driven axle of the vehicle. Starting procedure for the vehicle, too takes place with help of said additional highest-speed step gear and with, a correspondingly high slipping of the clutch. Only during a second step does engagement of the first gear take place.